United States
Environmental Protection
Agency
Atmospheric Research and
Exposure Assessment Laboratory
Research Triangle Park NC 27711
Research and Development
EPA/600/S8-90/069 June 1991
Project Summary
User's Guide for Executing
OZIPR
M.W. Gery and R.R. Grouse
A new, trajectory-type, air quality
simulation model called OZIPR has been
developed. OZIPR Is based on previous
versions of EPA's Ozone Isopleth Plot-
ting Program (OZIPP) Model but con-
tains Improved and expanded capabili-
ties that make the model useful for re-
search purposes. OZIPR serves the dual
purpose of providing: (1) a simple tra-
jectory model capable of using complex
chemical mechanisms, emissions, and
various meteorological parameters, and
(2) procedures through which the Em-
pirical Kinetics Modeling Approach
(EKMA) can be implemented to calcu-
late emission reductions for compliance
with the National Ambient Air Quality
Standard for ozone. While these capa-
bilities were included in earlier versions
of OZIPP, the new OZIPR contains ma-
jor improvements that expand the
program's capability to input, utilize,
and output a much larger range of In-
formation.
The Project Report serves as a user's
manual for OZIPR. It contains a descrip-
tion of the model, along with input and
output requirements and options. The
input and output files for nine examples
are also included. A floppy disk of the
executable program, the code, and input
and output files are provided.
This Project Summary was devel-
oped by EPA's Atmospheric Research
and Exposure Assessment Laboratory,
Research Triangle Park, NC, to an-
nounce key findings of the research
project that is fully documented In a
separate report of the same title (see
Project Report ordering Information at
back).
Introduction
This project consisted of the develop-
ment of a new, research-oriented version
of EPA's OZIPP (Ozone isopleth Plotting
Program) computer program. The OZIPP
series of programs employs a trajectory-
based air quality simulation model, in con-
junction with the Empirical Kinetics Model-
ing Approach (EKMA), to relate ozone
concentrations to emissions of volatile or-
ganic compounds (VOC) and oxides of
nitrogen (NOJ. While the aim of earlier
versions was to provide a rigid structure
within which State Implementation Plans
could be formulated, the goal of OZIPR is
to furnish a more comprehensive research
tool that is of use to Agency planners and
model developers. This version, called
OZIPR (R for research), is specifically en-
hanced to provide more complex input,
output, and calculation capabilities than
exist in the earlier versions.
Description of OZIPR
OZIPR simulates the complex chemi-
cal and physical processes of the lower
atmosphere through use of a trajectory
model. The physical representation is a
well-mixed column of air extending from
the ground to the top of the mixed layer.
This idealized air column moves with the
wind (along the wind trajectory) but cannot
expand horizontally. Emissions from the
surface are included as the air column
passes over different sources, and air from
above the column is mixed in as the inver-
sion rises during the day. Very complex
chemical mechanisms may be used with
OZIPR to describe the chemical processes
that occur within the modeled air mass.
Oy() Printed on Recycled Paper
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Besides individual wind trajectory
simulations, the program can use the EKMA
procedure to automatically estimate the
amount and type of precursor emission
reductions expected to achieve a specified
ozone level. In this procedure, OZIPR
performs multiple simulations with different
levels of organic and NOX precursor emis-
sions to estimate the effect of reduced
emissions on maximum ozone concentra-
tions. The program can also perform a
specified set of simulations used to calcu-
late ozone levels at fixed intervals. This
allows for the plotting of fixed ozone con-
centration lines (isolines) as a function of
initial precursor and emission levels.
Although the structure of the program
is similar to earlier versions of OZIPP,
OZIPR was enhanced in this study to pro-
vide expanded yet simpler input capability,
more calculation options, greater calculation
speed, and enhanced output options. These
improvements are described in the follow-
ing sections:
Using OZIPR
The structure of OZIPR has been al-
tered to execute in batch mode on a per-
sonal or mainframe computer. Fixed-col-
umn oriented input has been eliminated in
favor of free-format style. In addition, many
redundant options were eliminated, and a
new command structure was devised. The
input file is a text file consisting of a series
of OPTIONS and COMMANDS. In addition,
the input file can contain the names of
commonly used "include" files that are in-
serted into the text of the input file. This is
done by inserting the character u@," fol-
lowed by the complete filename of an in-
clude file at the location in the input file
where the text of the include file is desired.
Comments are also now allowed on input
between {} and (), or on lines with the first
character"!."
In previous versions of OZIPP, a fixed
amount of input was allowed for each op-
tion, such as 20 photolysis reactions, or 24
hours of temperature, etc. These numbers
were deeply buried in the computer code
and could not be changed. One result of
this study was to uncover these numbers
and bring them to the top of the program
so that they may now be easily changed if
the user wishes to expand the program's
capabilities. The parameters that can now
be easily varied and their current limits are:
Hours of input «• 24
Total Reactions « 160
Photolysis Reactions - 23
Reaction Products - 12
Total Species » 65
VOC Species - 20
Emitted Species - 10
Isopleth Species • 12
Deposition Species - 10
Printed Species Names « 20
Average Species Names * 10
Dump Names « 12
Dump Rates « 12
Filed Species Names - 20
Command Options
The command options were reorga-
nized and enhanced in OZIPR. The fol-
lowing list summarizes the improved fea-
tures added in this project:
ECHO of input commands into the out-
put file.
Optional output printer WIDTH of 80 or
132 columns.
Optional listing of the chemical mecha-
nism used, a list of rate constants at
standard conditions, and a list of the
kinetic expressions and rate parameters.
Expanded chemical MECHANISM input,
including:
Elimination of the default CBM-IV
Mechanism;
Free format input of reactions and
kinetics for any mechanism;
Use of N2, O2, and M as known con-
centrations;
Three reactants and twelve products
with stoichiometry;
Negative product stoichiometry;
Kinetics in either ppm-min or molec-
cc-sec units;
Standard kinetic expressions such as
k - A x (T/300)8 x e^ ;
Falloff type kinetic expressions;
Special kinetic expressions designed
to represent unique pressure and
temperature dependency;
Linear dependence of one rate on
another;
Calculation of reverse equilibrium rates
using the equilibrium constant as
input;
Dependence of reaction rates on so-
lar zenith angle and spectral distri-
bution of actinic flux.
Tabular input of either absolute or rela-
tive solar ZENITH angle dependence for
rate constants.
Expanded input for METEOROLOGICAL
conditions, including:
Free format input of all options;
Dilution curve or hourly mixing height
input;
Temperature table input;
User supplied atmospheric pressure;
Water vapor concentration from either
concentration or relative humidity
tables;
Simplified input of constant tempera-
ture, pressure, and water levels.
New grouping of input for BOUNDARY
conditions input, including:
Free format input of all options;
VOC reactivity;
Optional NO-to-NO2 ratios for both ini-
tial and emitted NOX;
Input of surface and aloft transported
levels of O3, VOC, NOX1 and CO;
Input of surface and aloft transported
concentrations other than the spe-
cific controllable substances noted
above;
Expanded deposition rate profiles;
Simplified input of constant deposition
rates.
Reformulated EMISSIONS options, in-
cluding:
Elimination of the MOLE option;
Simplification of MASS type input (kg/
km2/hr);
Expansion of the MASS option to al-
low input of mass emissions for any
species;
Printed hourly output of both emission
ratios and mass per unit area emis-
sions for each emitted species;
Improvement of the emission algo-
rithm to account for changing MASS
emission rates with changing tem-
perature and pressure;
Simplified input of CO emissions.
CO is now included as a main, control-
lable species (like NOX and VOC) in the
CALC, EKMA and ISOP commands.
Expanded user control of output charac-
teristics for the single CALCULATION
option, including:
Print control options allowing individual
control over specific aspects of out-
put, such as printing of concentra-
tions, net rates of change of spe-
cies, hourly photolysis rates, and
net rates of each reaction;
Time control of first printing of output
and time interval between printing
output;
Printing of concentrations for only a
limited number of species;
Calculation of the maximum concen-
tration of a variable number of spe-
cies over a user supplied time inter-
val (e.g., an 8-hour average maxi-
mum);
Optional table of hourly concentrations
or reaction rates printed at the end
of the simulation;
Optional output of concentrations for
user specified species in a file suit-
able for importing into spreadsheet
programs.
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Reorganization and expanded user op-
tions for the EKMA option, including:
Inclusion of CO directly in the EKMA
command;
Ability to reduce future CO emissions;
Merger of EKMA and EMISSIONS
options for CO;
Input of future surface and aloft
transported O3, VOC, NO,, and CO;
New formulation for generating incre-
mental VOC, CO, or NOX reduction
tables;
Optional input of the number of tries
for program to attempt solution of
design and control convergence.
Minimization of computer code size and
increase in speed by removing isopleth
diagram generation from OZIPR and
creating a post-processor program
named ISOPLOT.
Expansion of isopleth plotting options,
user interaction, and provisions for high
quality graphics output in the ISOPLOT
program.
Examples
Input and output files are provided for
nine examples, along with the program
source and executable files. The examples
use three different chemical kinetics
mechanisms, all major inputs, functions,
and output options.
Summary
An expanded, research-oriented ver-
sion of EPA's OZIPP computer program
has been developed. The new program,
OZIPR, allows increased input of informa-
tion, including free-format input of chemi-
cal kinetics mechanisms, and extensive
expansion of kinetics input and optional
output. The use of the computer code is
fully described in the user's manual.
•&U.S. GOVERNMENT PRINTING OFFICE: 1991 - 548-028/40009
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M. W. Gery is with Atmospheric Research Associates, Inc., Boston, MA 02116.
R.R. Grouse is at the University of North Carolina, School of Public Health, Chapel Hill,
NC 27599.
Marcla C. Dodge is the EPA Project Officer (see below).
The complete report, entitled "User's Guide for Executing OZIPR," (Order No. PB91-
175877/AS; Cost: $23.00, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Atmospheric Research and Exposure Assessment Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati, OH 45268
BULK RATE
POSTAGE & FEES PAID
EPA PERMIT NO. G-35
Official Business
Penalty for Private Use $300
EPA/600/S8-90/069
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